1. Field of the Invention
The invention relates to a technique for displaying images in which code information is embedded.
2. Description of the Related Art
There are techniques for correlating a geometric pattern drawn in an image, for example, a bar code or a two-dimensional bar code, to code information. A bar code or a two-dimensional bar code is a geometric pattern and is visually meaningless to a human.
There is a technique called steganography for embedding code information in image information and extracting the code information by a recipient of the image information. There is one steganography technique in which image information is divided into a plurality of blocks, and code information is embedded using the relationships between the feature values (for example, the average density, the granularity, the chroma, and the barycenter or variance of densities) of the individual blocks. A technique related to the above techniques is disclosed in Japanese Laid-open Patent Publication No. 2006-60856 and Japanese Laid-open Patent Publication No. 2004-96310.
When code information is embedded in image information, for example, the color information of the image information is changed. When the image is printed, the size of the printed image is fixed, and thus the image quality can be adjusted in advance. However, the image may be displayed on a display. In this case, when the image, which is enlarged because the display is large, is displayed, a part of the image where the code information is embedded may be noticeable.